I'm going to get my 9-year old son the MMR, which he has never had. Does he need one dose or two? And if two, how far apart should they be? And at what age would you give him the CP vax? Thanks so much.

1 dose of MMR has a 95% chance of working. The regular schedule, however, calls for two doses (at least 1 month apart) in order to increase that effectiveness to 98%. I don't think that second dose is necessary though - one should be fine.

As for Cpox, 1 dose is 85% to 95% effective. A second dose, at least 3 months apart, is the basic recommendation. But in my opinion, 1 dose works well enough. If he did end up catching Cpox, the vaccine would likely make it a mild case anyway. But if you want more guaranteed protection, you'd get both doses.